ARM processor mode, kernel startup, Hyp / secure state

[Ian Jackson]

Will Deacon writes ("Re: ARM processor mode, kernel startup, Hyp / secure state"):
> From discussions that I've been having with the technical architects at ARM
> and various bootloader people, it looks like we have two scenarios [this is
> reiterating a lot of what you've said but I think it's important]:

Right.

>   After the system has taken care of whatever secure initialisation was
>   required, it moves into HYP mode. At this point there are two things that
>   can happen:
> 
>   1.0: HYP mode boot loader (uboot, UEFI) runs and installs Linux at the
>        same privilege level
>   1.1: Raw Linux boots, and detects HYP mode
>   1.2: Sets up basic init, with HVC trampoline for installing KVM/Xen later
>   1.3: Switch to SVC mode
>   1.4: Continue booting Linux as normal

Since we have discovered that this approach will work fine with
existing kernels, even ones which are completely unaware of Hyp mode,
I think this is the right approach.  It can be implemented by boot
loaders etc. right away.

Ian.